B-IFDMA Configuration for Unlicensed Band Operation

ABSTRACT

Various communication systems may benefit from appropriate handling of uplink communications. For example, certain wireless communication systems may benefit from an uplink coverage extension for unlicensed band operation. A method can include configuring a first interlace having a first starting physical resource block. The method can also include configuring a second interlace having a second starting physical resource block offset from the first physical resource block. The method can further include transmitting or receiving a signal based on a combination of the first interlace and the second interlace. The combination can include at least one cluster but less than two clusters in each measurement interval.

BACKGROUND Field

Various communication systems may benefit from appropriate handling ofuplink communications. For example, certain wireless communicationsystems may benefit from an uplink coverage extension for unlicensedband operation.

Description of the Related Art

Release 13 (Rel-13) of long term evolution (LTE) licensed assistedaccess (LAA) may provide licensed-assisted access to unlicensed spectrumwhile coexisting with other technologies and fulfilling regulatoryrequirements. In Rel-13 LAA, unlicensed spectrum may be utilized toimprove LTE downlink (DL) throughput.

In Rel-13, one or more LAA DL secondary cells (SCells) may be configuredto a user equipment (UE) as part of DL carrier aggregation (CA)configuration, while a primary cell (PCell) may need to be on licensedspectrum. LTE LAA may evolve to support LAA UL transmissions onunlicensed spectrum in LTE Rel-14.

Standardized LTE LAA approach in Rel-13 based on CA framework assumestransmission of uplink control information (UCI) on PCell in a licensedband. However, LAA may be extended with uplink support includingphysical uplink control channel (PUCCH), as well as in dual connectivityoperation. Thus, certain approaches may allow for non-ideal backhaulbetween PCell in licensed spectrum and SCell(s) in unlicensed spectrum.A 3GPP Rel-14 Work Item introduces LAA UL support (Enhanced LAA for LTE,RP-152272, the entirety of which is hereby incorporated herein byreference.

Furthermore, there may be standalone LTE operation on unlicensedspectrum. LTE standalone operation on unlicensed spectrum means thatevolved Node B (eNB)/UE air interface may rely solely on unlicensedspectrum without any carrier on licensed spectrum. MulteFire (MLF) maybe an example of a system that incorporates standalone LTE operation onunlicensed spectrum.

In LTE operation on unlicensed carriers, depending on the regulatoryrules, the UE may need to perform listen before talk (LBT) prior to anyUL transmission. Some exceptions may exist though. For example, at leastin some regions, transmission of acknowledgment/negative acknowledgement(ACK/NACK) feedback may be possible without LBT when immediatelyfollowing a DL transmission, similar to WiFi operation. Short controlsignaling (SCS) rules defined for Europe by ETSI may allow fortransmission of control signaling with a duty cycle of no more than 5%over 50 ms period without performing LBT:

Definition: Short Control Signalling Transmissions are transmissionsused by Adaptive equipment to send management and control frames (e.g.ACK/NACK signals) without sensing the channel for the presence of othersignals. NOTE: It is not required for adaptive equipment to implementShort Control Signalling Transmissions. If implemented, short controlsignaling transmissions of adaptive equipment may need to have a maximumduty cycle of 5% within an observation period of 50 ms.

Additionally, at least in some regions, scheduled UL transmissions mayin general be allowed without LBT, when the transmission followsdirectly a DL transmission before which the eNB has performed LBT andtotal transmission time covering both DL and UL is limited by themaximum Tx burst time defined by the regulator.

Block interleaved orthogonal frequency division multiple access(B-IFDMA) is a baseline uplink transmission scheme that can be used foruplink transmission in unlicensed spectrum. Wideband transmission may berequired by the regulatory rules, such as ETSI, for example allsignal(s) may need to be easily detectable by neighboring nodes.

FIG. 1 shows the principle of physical uplink shared channel (PUSCH)transmission according to B-IFDMA on interlaces having 10 equally spacedclusters. The approach shown in FIG. 1 may ensure good coexistence withLTE, in terms of physical resource block (PRB) granularity. The approachin FIG. 1 may also provide good multiplexing capacity: up-to 10 parallelinterlaces. This approach may also provide good resource scalability bymeans of variable cluster size, in terms of a cluster size of variable xPRBs. The approach may also provide fixed size resource for allinterlaces with given cluster size. Other benefits of such an approachmay include good support for PUCCH/PUSCH multiplexing and compatibilitywith ETSI bandwidth occupancy rules.

Unlicensed band usage can involve different regulatory rules which aimat fair and equal spectrum usage for different devices. Those rules mayinvolve limitations related to occupied channel bandwidth. For example,in ETSI Standard (ETSI EN 301 893, v.1.7.1): “The Nominal ChannelBandwidth shall be at least 5 MHz at all times. The Occupied ChannelBandwidth shall be between 80% and 100% of the declared Nominal ChannelBandwidth. In case of smart antenna systems (devices with multipletransmit chains) each of the transmit chains shall meet thisrequirement.”

The rules on unlicensed band usage may also include limitations relatedto maximum power spectral density (PSD). Maximum PSD requirements existin many different regions (see e.g. 3GPP TR 36.889). For example, therequirement may be stated with a resolution bandwidth of 1 MHz. The ETSI301 893 specification, for example, requires 10 dBm/MHz for 5150-5350MHz. Similar limitations are involved also in other places. For example,peak UE's PSD for 5.15-5.725 MHz is 11 dBm/MHz in USA.

FIG. 2 illustrates B-IFDMA with 6 interlaces. In this example, clustersize=1 PRB, 20 MHz. This design, illustrated in FIG. 2, is based on 6interlaces, each having 16 or 17 clusters.

The maximum Tx power for this approach can be calculated as shown inTable 1:

TABLE 1 a Max PSD 11 dBm/MHz b Max Tx power with 18 23.55 dB b = a +10*log10(18) clusters/18 MHz c Max power with 16 23.04 dB c = a +10*log10 (16) clusters/18 MHz d Max power loss 0.51 dB d = b − c

As shown in Table 1, maximum power loss with 6 interlaces may be only0.51 dB. On the other hand, the design with 6 interlaces may only permitsix users to be multiplexed in frequency domain. However, multiplexingmay involve both control and data channels. Moreover, in a TDD system, acertain UL subframe may need to convey UL control channel for multipleUEs and multiples subframes. There may also be a need to support variousservices including voice over internet protocol (VoIP). All thesehighlight the importance of having high multiplexing capability.

Additionally, resource size in terms of number of PRBs can vary frominterlace-to-interlace. Usage of multiple resource sizes may complicatethe system design, especially control plane. For example, in the exampleillustrated in FIG. 2 there may be four interlaces with 17 PRBs and twointerlaces with 16 PRBs.

It may also not be possible to consider fixed size resources on top ofsix interlaces. According to this principle, resource size may be 16PRBs per interlace. This means that there may be four unused PRBS,corresponding to 4% additional overhead in 100 MHz bandwidth.

BRIEF DESCRIPTION OF THE DRAWINGS

For proper understanding of the invention, reference should be made tothe accompanying drawings, wherein:

FIG. 1 shows the principle of PUSCH transmission according to B-IFDMA oninterlaces having 10 equally spaced clusters.

FIG. 2 illustrates B-IFDMA with 6 interlaces.

FIG. 3 illustrates a B-IFDMA design based on 10 interlaces, according tocertain embodiments.

FIG. 4 illustrates a combination of two B-IFDMA interlaces, according tocertain embodiments.

FIG. 5 illustrates B-IFDMA interlace A+B with respect to a measurementinterval, according to certain embodiments.

FIG. 6 illustrates P_(loss,AB) and P_(max,AB) as a function of clustersize, x, according to certain embodiments.

FIG. 7 illustrates an example of measurement of B-IFDMA interlace A+B,according to certain embodiments.

FIG. 8 illustrates predefined clusters, according to certainembodiments.

FIG. 9 illustrates a method according to certain embodiments.

FIG. 10 illustrates a system according to certain embodiments.

DETAILED DESCRIPTION

Certain embodiments relate to uplink (UL) transmission on unlicensedspectrum subject to listen-before-talk rules. Certain embodimentsprovide a solution for UL coverage extension when operating according toregulatory rules related to limited power spectral density, such asdBm/MHz. Certain embodiments may also be applicable to 3GPP LTE licensedassisted access enhancements, such as support for uplink operation, aswell as possible stand-alone operation on unlicensed carriers.

Certain embodiments may specifically address maximum PSD limitations,which may be imposed by regulators. Without proper design, a signal withsmall transmission bandwidth, such as an UL control signal, may belimited by peak PSD. This may lead to reduced transmission power andreduced coverage. In standalone operation, such as MLF, cell coveragemay be limited by UL control channels, such as random access (RA)preamble, physical uplink control channel (PUCCH) hybrid automaticrepeat request acknowledgment (HARQ-ACK), and scheduling request (SR),especially when using short PUCCH.

More particularly, certain embodiments may provide an UL coverageextension solution when operating according to PSD-limitation inunlicensed spectrum and when multiples of 10 interlaces/clusters areapplied in the transmission. Thus, certain embodiments may use a B-IFDMAdesign based on 10 interlaces. FIG. 3 illustrates a B-IFDMA design basedon 10 interlaces, according to certain embodiments.

As shown in FIG. 3, the 1st interlace is considered, shown using shadingat blocks 0, 10, 20, 30, and so on. Resolution bandwidth used in PSDmeasurement can be 1 MHz. Thus, FIG. 2 illustrates B-IFDMA with 10interlaces, cluster size=1 PRB, 20 MHz nominal system bandwidth, 18 MHzoccupied bandwidth, 100 PRBs, 180 KHz each.

The maximum transmission (Tx) power with 20 MHz nominal systembandwidth, 18 MHz occupied Bandwidth (100 PRBs, 180 KHz each) can becalculated as shown in Table 2:

TABLE 2 a Max PSD 11 dBm/MHz b Max Tx power with 18 23.55 dB b = a +10*log10(18) clusters/18 MHz c Max power with 10 21.00 dB c = a +10*log10 (10) clusters/18 MHz d Max power loss 2.55 dB d = b − c

The example in Table 2 shows that a design with ten clusters mayexperience 2.6 dB power loss compared to maximum achievable Tx powerwith LTE numerology, including spectrum usage efficiency of 0.9. Thisloss may be due to the fact that some of the 1-MHz Measurement intervalswill not be used for transmission because the cluster spacing is largerthan 1 MHz. In other words, optimal transmit power, in terms of PSD on aper-PRB level, may be reached when the number of clusters is equal to18, assuming 18 MHz bandwidth, e.g. 100 PRBs, 180 KHz each.

Alternatively, if the number of clusters is larger than 18, some of the1-MHz measurement intervals may contain more 180 KHz or 1 PRB of PUSCH,and maximum PSD may be defined according to those measurement intervals.This approach may also lead to a loss in maximum transmit power as thePSD per PRB may need to be reduced for all clusters.

Certain embodiments provide a specific configuration for UL coverageextension when operating according to PSD-limitation in unlicensedspectrum. In the certain embodiments, UL transmission includes twoB-IFDMA interlaces both occupying every tenth PRB. A first interlace,interlace A, can start at PRB a. A second interlace, interlace B, canstart at offset b=a+5.

In certain embodiments, a∈[0, 1, 2, 3, 4]. Two B-IFDMA interlaces tiedtogether can be considered as a single resource, namely “B-IFDMAinterlace A+B.”

Cluster size of Interlace A and Interlace B can be the same. The sizecan be expressed as parameter x, where x∈[1, 2, 3, 4].

FIG. 4 illustrates a combination of two B-IFDMA interlaces, according tocertain embodiments. In this example, cluster size=1 PRB, 20 MHz. As canbe seen from the different shadings, the combined B-IFDMA interlace A+Bcan include both interlace A at blocks 2, 12, and so on, as well asinterlace B at blocks 7, 17, and so on.

The signal structure B-IFDMA interlace A+B can have the property thatthe signal has at least one cluster but less than two clusters withineach measurement interval, such as 1 MHz. The measurement intervals canbe within the used channel bandwidth, for example 0.9*nominal bandwidth.In other words, the spacing between clusters can be less than or equalto the measurement interval, and cluster spacing plus cluster size canbe larger than the measurement interval. Further, clusters can be evenlyspaced.

The feature of having at least one cluster but less than two clusterscan refer to a situation in which the portion of the signal that iswithin a measurement interval can have bandwidth of at least one clusterbut less than two full clusters. The signal portion may belong to one ortwo physical clusters of one B-IFDMA interlace A+B signal.

These properties may allow definition of reasonable power control (PC)rules to meet the PSD limit given by a regulator.

FIG. 5 illustrates B-IFDMA interlace A+B with respect to a measurementinterval, according to certain embodiments. In this example, themeasurement interval is 1 MHz.

Certain embodiments may specially handle the usage of B-IFDMA interlaceA+B. The usage can include UL power control setting, which can bereferred to as solution #1 and/or cluster-specific power control anddropping, which can be referred to as solution #2. Thus, these twosolutions can be used either alone or in combination.

The first solution can be based on a specific way for determining themaximum transmission power value when applying B-IFDMA interlace A+B.The final maximum transmission power may further be limited byregulatory or specification limitation on the maximum transmissionpower. The maximum transmission power value when applying B-IFDMAinterlace A+B can be denoted as P_(max,AB).

The value, P_(max,AB), can be defined in such a way that maximum PSDdoes not exceed the given limit in any of the measurement intervals,such as a 1 MHz bandwidth portion. The value, P_(max,AB), can be definedby means of the following terms: max PSD/measurement interval, PSD_(max)(dBm/MHz), which can be given by the regulator; channel bandwidth, ChBW(MHz), which may be, for example, either 20 MHz or 10 MHz and caninclude 100 or 50 PRBs in, for example, LTE; and required power loss orpower reduction, denoted as P_(loss,AB).

In order to meet the PSD requirement, P_(loss,AB) can be determinedaccording to following equation, assuming ChBW=20 MHz, and measurementinterval equal to 1 MHz:P_(loss,AB)=10*log10((100/18−5+X))−10*log10(number_of_clusters/number_of_measurement_intervals),where measurement bandwidth in PRBs equals to 1 MHz (i.e. 100 PRBs/18MHz) and the occupied signal bandwidth corresponds to at least onecluster but less than two clusters within each measurement interval (1MHz) corresponding to the used channel bandwidth (=0.9*nominalbandwidth). The cluster size can equal X and the constant 5 cancorrespond to the cluster spacing/offset between interlaces.

With the given assumptions, P_(loss,AB) can be generalized to anymeasurement bandwidth of z PRBs:P_(loss,AB)=10*log10((z−5+X))−10*log10(number_of_clusters/number_of_measurement_intervals).

P_(max,AB) can be then obtained as the following:

${P_{\max \;,{AB}}({dBm})} = {{{PSD}_{\max}\frac{dBm}{({MHz})}} + {10*\log \; 10\left( {0.9*{ChBW}} \right)} - {P_{{loss},{AB}}.}}$

When applying B-IFDMA interlace A+B with cluster size x=1, and withPSD_(max)=11 dBm/MHz, P_(max,AB) can be obtained as shown in Table 3:

TABLE 3 A PSD_(max) 11 dBm/MHz B P_(psd) _(—) _(max =) PSD_(max) + 23.55dBm b = a + 10*log10(18) 10*log10(0.9*ChBW) C P_(loss, AB) 1.46 dB c =10*log10(100/18 − 5 + 1) − 10*log10(20/18) D P_(max, AB) 22.09 dBm d = b− c

The calculation in Table 3 shows that maximum power loss with B-IFDMAinterlace A+B is 1.09 dB (2.55-1.46) smaller compared to B-IFDMAinterlace A or B. Also, P_(loss,AB) reduces further, when increasing thecluster size x, as will be seen below. Furthermore, when compared to thecase with 6 interlaces, and correspondingly 16 or 17 clusters, thenumber of available resource elements is also higher, allowing forhigher coding gain.

The second solution can be based on cluster-specific power controland/or dropping for B-IFDMA interlace A+B. This approach can include thefollowing steps: determine the initial Tx power value, denoted asP_(unlimited), for UL transmission based on e.g. the current PC rules;and determine P_(ltd), by upper-limiting P_(unlimited) by P_(psd_max),which can correspond to maximum Tx power value with the PSD limit, whereP_(ltd)=min (P_(unlimited), P_(psd_max)) andP_(psd_max)=PSD_(max)+10*log10(0.9*ChBW).

The second approach also include the following steps: determine Max Txpower for current B-IFDMA interlace A+B according to the first solution,discussed above, where max Tx power for current B-IFDMA interlace A+Bcan be denoted as P_(max,AB); and if P_(max,AB)<P_(psd_max) thendetermine which of the measurement intervals contain more than one 1cluster.

In the second approach, special handling can be applied for predefinedclusters or PRBs corresponding to each determined measurement interval.After special handling, each measurement interval can fulfil the PSDlimit. Special handling can include PRB dropping, PRB-specific powerreduction and subcarrier dropping, as discussed below.

The first and second solutions can be various implemented. The followingare some non-limiting examples.

Referring again to the first solution, FIG. 6 shows P_(loss,AB) andP_(max,AB) for B-IFDMA interlace A+B assuming that measurement intervalequals 1 MHz, PSD_(max) corresponds to 11 dBm/MHz and x varies between 1and 5. Thus, FIG. 6 illustrates P_(loss,AB) and P_(max,AB) as a functionof cluster size, x, according to certain embodiments.

In certain embodiments, B-IFDMA interlace A+B is applied only forcertain UEs/channels. For example, B-IFDMA interlace A+B may be appliedonly to UEs located at the cell edge and/or UEs experiencingPSD-limitation.

A UE may receive information on the maximum PSD or on the maximumtransmission power per frequency measurement interval, e.g. 11 dBm/MHz,that is allowed on the cell or network from the system information. TheUE can adjust the transmission power according to the transmission powercontrol that incorporates the received limits on the maximum PSD or onthe maximum transmission power per measurement interval. The UEexperiences PSD-limitation when the UE limits the transmission power dueto the received maximum PSD limit.

Usage of B-IFDMA interlace A+B can be fully controlled by an accessnode, such as an eNB. For example, for PUCCH/PUSCH the eNB may selectB-IFDMA interlace A+B based on UL measurement and/or feedback, includede.g. on power headroom reporting, from UE. By contrast, for RA preamblethe selection may be done by the UE based on DL path loss measurementand predetermined rules obtained from the system information.

B-IFDMA interlace A+B may apply similar formats as regular B-IFDMAinterlace, such as A or B considered individually. Thus, Interlace A+Bmay apply either sequence modulation or (DFT-S-)OFDMA.

As mentioned above, the second solution can involve PRB or subcarrierdropping. This dropping can reduce the number of resource elementsavailable within B-IFDMA interlace A+B. This can be done in adeterministic manner provided that both UE and eNB follow the samedropping rules.

FIG. 7 illustrates an example of measurement of B-IFDMA interlace A+B,according to certain embodiments. In this example, (20 MHz, x=1) thereare four measurement intervals (#1, #2, #10, #11) considered asdetermined measurement intervals having more than one cluster. Moreover,there are in total six clusters located within the determinedmeasurement intervals.

FIG. 8 illustrates predefined clusters, according to certainembodiments. As shown in FIG. 8, clusters located with PRBs 5 and 55 canbe considered as predefined clusters. They can be, for example, droppedcompletely. This dropping can be considered special handling, asmentioned above. After dropping, all measurement intervals may containat most one cluster.

Special handling can be applied to one or more clusters corresponding todetermined measurement intervals. PRB dropping can correspond to anoperation where a certain PRB is not transmitted at all. Subcarrierdropping can be similar to PRB dropping. Subcarriers that are nottransmitted can be selected with the granularity of onesubcarrier/resource element, instead of PRB.

PRB/cluster-specific power control can correspond to a power controlwhere Tx power or power spectral density of a predefined PRB/clusterwithin a determined measurement interval can be reduced such that a PSDlimit for each measurement interval is fulfilled.

There may be various ways to find or otherwise determine measurementintervals with more than one cluster. The following, therefore, is anexample of how to find determined measurement intervals. This examplerelates to scenario with 20 MHz, 100 PRBs, measurement interval=1 MHz.

In this example, j=relative cluster index of B-IFDMA interlace A+B (0,1, . . . , 19); m(j)=PRB index of cluster index. m(j) ∈[0, 1, . . . ,99]; and n=measurement interval index (0, 1, . . . , 19).

The determination may begin by determining a measurement interval indexfor each cluster, n(j)=floor (m(j)/(100/18)). Then, it can be determinethat special handling may be required for cluster j if n(j)=n(j+1), forany j. Otherwise, no special handling may be required.

FIG. 9 illustrates a method according to certain embodiments. As shownin FIG. 8, a method can include, at 910, configuring a first interlacehaving a first starting physical resource block. This first interlacemay be Interlace A discussed above. The method can also include, at 920,configuring a second interlace having a second starting physicalresource block offset from the first physical resource block. Thissecond interlace may be Interlace B discussed above. The configuring canbe done any desired way, such as a manufacturer configuration, a networkupdate, a manual configuration, or software-based configuration. Othermechanisms are also permitted. The configuration can be done by anaccess node, such as an eNodeB. The eNodeB can indicate to the UE withPDCCH UL grant the interlaces A and B. Other mechanisms are alsopermitted.

The method can further include, at 930, communicating (for example,transmitting and/or receiving) a signal based on a combination of thefirst interlace and the second interlace. The combination can include atleast one cluster but less than two clusters in each measurementinterval. The combination may be B-IFDMA interlace A+B, as discussedabove. For example, both the first interlace and the second interlacecan be block interleaved frequency division multiple access interlaces,for example as illustrated in FIG. 4.

The communication at 930 can be variously implemented. For example, a UEcan transmit the signal according to the configuration received from theeNB in 910 and 920, the eNodeB can receive the signal.

The transmitting or receiving the signal based on the combination of thefirst interlace and the second interlace can be contingent on at leastone of a corresponding user equipment being located at a cell edge orthe corresponding user equipment experiencing power spectral densitylimitation. Other user equipment specific bases for applying thiscombination to, for example, uplink communications are also permitted.

A cluster size of the first interlace can be the same as a cluster sizeof the second interlace. Other sizes are also permitted.

A power spectral density of the signal can be controlled to avoidexceeding a predetermined limit in any measurement interval. This maydone by, for example, the first solution described above. Control of thepower spectral density can be configured to take into account maximumpower spectral density per measurement interval. The control of thepower spectral density can also or alternatively be configured to takeinto account channel bandwidth. The control of the power spectraldensity can also or alternatively be configured to take into accountrequired power reduction. The control of the power spectral density maybe incorporated into a transmission power control procedure.

In certain embodiments, the signal can be controlledcluster-specifically. This may, for example, follow the second solution.Accordingly, the signal can be controlled based on cluster-specificpower control and/or based on cluster-specific dropping.

The cluster-specific control can take into account an initial unlimitedtransmission power level. The cluster-specific control can also takeinto account a maximum transmission power level within a power spectraldensity limit. The method can further include, at 940, determiningwhether a measurement interval contains more than one cluster and, at945, applying special handling for predefined clusters corresponding tothe determined measurement interval.

The special handling can be configured to ensure that a power spectraldensity limit is fulfilled for the determined measurement interval. Thespecial handling can include at least one of physical resource blockdropping, physical resource block specific power reduction, orsubcarrier dropping.

FIG. 10 illustrates a system according to certain embodiments of theinvention. It should be understood that each block of the flowchart ofFIG. 9 may be implemented by various means or their combinations, suchas hardware, software, firmware, one or more processors and/orcircuitry. In one embodiment, a system may include several devices, suchas, for example, network element 1010 and user equipment (UE) or userdevice 1020. The system may include more than one UE 1020 and more thanone network element 1010, although only one of each is shown for thepurposes of illustration. A network element can be an access point, abase station, an eNode B (eNB), or any other network element. Each ofthese devices may include at least one processor or control unit ormodule, respectively indicated as 1014 and 1024. At least one memory maybe provided in each device, and indicated as 1015 and 1025,respectively. The memory may include computer program instructions orcomputer code contained therein, for example for carrying out theembodiments described above. One or more transceiver 1016 and 1026 maybe provided, and each device may also include an antenna, respectivelyillustrated as 1017 and 1027. Although only one antenna each is shown,many antennas and multiple antenna elements may be provided to each ofthe devices. Other configurations of these devices, for example, may beprovided. For example, network element 1010 and UE 1020 may beadditionally configured for wired communication, in addition to wirelesscommunication, and in such a case antennas 1017 and 1027 may illustrateany form of communication hardware, without being limited to merely anantenna.

Transceivers 1016 and 1026 may each, independently, be a transmitter, areceiver, or both a transmitter and a receiver, or a unit or device thatmay be configured both for transmission and reception. The transmitterand/or receiver (as far as radio parts are concerned) may also beimplemented as a remote radio head which is not located in the deviceitself, but in a mast, for example. It should also be appreciated thataccording to the “liquid” or flexible radio concept, the operations andfunctionalities may be performed in different entities, such as nodes,hosts or servers, in a flexible manner. In other words, division oflabor may vary case by case. One possible use is to make a networkelement to deliver local content. One or more functionalities may alsobe implemented as a virtual application that is provided as softwarethat can run on a server.

A user device or user equipment 1020 may be a mobile station (MS) suchas a mobile phone or smart phone or multimedia device, a computer, suchas a tablet, provided with wireless communication capabilities, personaldata or digital assistant (PDA) provided with wireless communicationcapabilities, portable media player, digital camera, pocket videocamera, navigation unit provided with wireless communicationcapabilities or any combinations thereof. The user device or userequipment 1020 may be a sensor or smart meter, or other device that mayusually be configured for a single location.

In an exemplifying embodiment, an apparatus, such as a node or userdevice, may include means for carrying out embodiments described abovein relation to FIGS. 4 through 9.

Processors 1014 and 1024 may be embodied by any computational or dataprocessing device, such as a central processing unit (CPU), digitalsignal processor (DSP), application specific integrated circuit (ASIC),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), digitally enhanced circuits, or comparable device or acombination thereof. The processors may be implemented as a singlecontroller, or a plurality of controllers or processors. Additionally,the processors may be implemented as a pool of processors in a localconfiguration, in a cloud configuration, or in a combination thereof.

For firmware or software, the implementation may include modules or unitof at least one chip set (e.g., procedures, functions, and so on).Memories 1015 and 1025 may independently be any suitable storage device,such as a non-transitory computer-readable medium. A hard disk drive(HDD), random access memory (RAM), flash memory, or other suitablememory may be used. The memories may be combined on a single integratedcircuit as the processor, or may be separate therefrom. Furthermore, thecomputer program instructions may be stored in the memory and which maybe processed by the processors can be any suitable form of computerprogram code, for example, a compiled or interpreted computer programwritten in any suitable programming language. The memory or data storageentity is typically internal but may also be external or a combinationthereof, such as in the case when additional memory capacity is obtainedfrom a service provider. The memory may be fixed or removable.

The memory and the computer program instructions may be configured, withthe processor for the particular device, to cause a hardware apparatussuch as network element 1010 and/or UE 1020, to perform any of theprocesses described above (see, for example, FIG. 9). Therefore, incertain embodiments, a non-transitory computer-readable medium may beencoded with computer instructions or one or more computer program (suchas added or updated software routine, applet or macro) that, whenexecuted in hardware, may perform a process such as one of the processesdescribed herein. Computer programs may be coded by a programminglanguage, which may be a high-level programming language, such asobjective-C, C, C++, C#, Java, etc., or a low-level programminglanguage, such as a machine language, or assembler. Alternatively,certain embodiments of the invention may be performed entirely inhardware.

Furthermore, although FIG. 10 illustrates a system including a networkelement 1010 and a UE 1020, embodiments of the invention may beapplicable to other configurations, and configurations involvingadditional elements, as illustrated and discussed herein. For example,multiple user equipment devices and multiple network elements may bepresent, or other nodes providing similar functionality, such as nodesthat combine the functionality of a user equipment and an access point,such as a relay node.

Certain embodiments may have various benefits and/or advantages. Forexample, uplink coverage can be improved without compromising the goodmultiplexing properties in certain embodiments. Moreover, certainembodiments can be fully compatible with 10 interlaces and 10 clusters,20 MHz. Certain embodiments may also fulfil ETSI bandwidth occupancyrule with maximum multiplexing capacity.

Additionally, in certain embodiments a combined interlace, such asB-IFDMA Interlace A+B, may be applied only by coverage limited UEs whilethe vast majority of UEs may apply 10 interlaces with bettermultiplexing properties.

One having ordinary skill in the art will readily understand that theinvention as discussed above may be practiced with steps in a differentorder, and/or with hardware elements in configurations which aredifferent than those which are disclosed. Therefore, although theinvention has been described based upon these preferred embodiments, itwould be apparent to those of skill in the art that certainmodifications, variations, and alternative constructions would beapparent, while remaining within the spirit and scope of the invention.

LIST OF ABBREVIATIONS

-   3GPP Third Generation Partnership Project-   ACK Acknowledgement-   ARI ACK/NACK resource Indicator-   B-IFDMA Block Interleaved Frequency Division Multiple Access-   BW BandWidth-   CA Carrier Aggregation-   CCE Control Channel Element-   CDM Code Division Multiplexing-   CRC Cyclic Redundancy Check-   CSI Channel State Information-   DCI Downlink Control Information-   DL Downlink-   eNB Evolved NodeB-   ETSI European Telecommunications Standards Institute-   FDD Frequency Division Duplex-   FDM Frequency Division Multiplex-   HARQ Hybrid Automatic Repeat Request-   IFDMA Interleaved Frequency Division Multiple Access-   LAA Licensed Assisted Access-   LBT Listen-Before-Talk-   LTE Long Term Evolution-   NACK Negative Acknowledgement-   OFDMA Orthogonal Frequency Division Multiplexing-   SC-FDMA Single-Carrier Frequency Division Multiplexing-   PCell Primary cell-   P-CSI Periodic Channel State Information-   PDSCH Physical Downlink Shared Control Channel-   PRACH Physical Random Access Channel-   PRB Physical Resource Block-   PUCCH Physical Uplink Control Channel-   PUSCH Physical Uplink Shared Channel-   RRC Radio Resource Control-   TDD Time Division Duplex-   TDM Time Division Multiplex-   Tx Transmission-   TXOP Transmission Opportunity-   UCI Uplink Control Information-   UE User Equipment-   UL Uplink-   DFT Discrete Fourier Transform-   PC Power Control

According to a first embodiment, a method can include configuring afirst interlace having a first starting physical resource block. Themethod can also include configuring a second interlace having a secondstarting physical resource block offset from the first physical resourceblock. The method can further include transmitting or receiving a signalbased on a combination of the first interlace and the second interlace.The combination can include at least one cluster but less than twoclusters in each measurement interval.

In a variant, the configuring the first interlace and the secondinterlace can include an access node sending a configuration in anuplink grant to a user equipment and the receiving the signal cancomprise receiving the signal at the access node from the userequipment.

In a variant, the configuring the first interlace and the secondinterlace can include a user equipment receiving from an access node aconfiguration in an uplink grant and the transmitting the signal cancomprise transmitting the signal to the access node from the userequipment.

In a variant, the first interlace and the second interlace are bothblock interleaved frequency division multiple access interlaces.

In a variant, the signal comprises an uplink signal.

In a variant, a cluster size of the first interlace is the same as acluster size of the second interlace.

In a variant, a power spectral density of the signal is controlled toavoid exceeding a predetermined limit in any measurement interval.

In a variant, control of the power spectral density is configured totake into account maximum power spectral density per measurementinterval.

In a variant, control of the power spectral density is configured totake into account channel bandwidth.

In a variant, control of the power spectral density is configured totake into account required power reduction.

In a variant, the signal is controlled cluster-specifically.

In a variant, the signal is controlled based on cluster-specific powercontrol.

In a variant, the signal is controlled based on cluster-specificdropping.

In a variant, the cluster-specific control can take into account aninitial unlimited transmission power level.

In a variant, the cluster-specific control can take into account amaximum transmission power level within a power spectral density limit.

In a variant, the method can include determining whether a measurementinterval contains more than one cluster and applying special handlingfor predefined clusters corresponding to the determined measurementinterval.

In a variant, the special handling is configured to ensure that a powerspectral density limit is fulfilled for the determined measurementinterval.

In a variant, the special handling comprises at least one of physicalresource block dropping, physical resource block specific powerreduction, or subcarrier dropping.

According to a second embodiment, an apparatus can include means forperforming the method according to the first embodiment, in any of itsvariants.

According to a third embodiment, an apparatus can include at least oneprocessor and at least one memory and computer program code. The atleast one memory and the computer program code can be configured to,with the at least one processor, cause the apparatus at least to performthe method according to the first embodiment, in any of its variants.

According to a fourth embodiment, a computer program product may encodeinstructions for performing a process including the method according tothe first embodiment, in any of its variants.

According to a fifth embodiment, a non-transitory computer readablemedium may encode instructions that, when executed in hardware, performa process including the method according to the first embodiment, in anyof its variants.

According to a sixth embodiment, a system may include two apparatuses,each according to the second or third embodiment, configured tocommunicate with one another using the signal.

The appendix attached herewith should be understood to be illustrativeand non-limiting, for improved understanding of the principles ofoperation of certain embodiments.

1. A method, comprising: configuring a first interlace having a firststarting physical resource block; configuring a second interlace havinga second starting physical resource block offset from the first physicalresource block; transmitting or receiving a signal based on acombination of the first interlace and the second interlace, wherein thecombination comprises at least one cluster but less than two clusters ineach measurement interval.
 2. The method of claim 1, wherein theconfiguring the first interlace and the second interlace comprises anaccess node sending a configuration in an uplink grant to a userequipment and the receiving the signal comprises receiving the signal atthe access node from the user equipment.
 3. The method of claim 1,wherein the configuring the first interlace and the second interlacecomprises a user equipment receiving from an access node a configurationin an uplink grant and the transmitting the signal comprisestransmitting the signal to the access node from the user equipment. 4.The method of claim 1, wherein the first interlace and the secondinterlace are both block interleaved frequency division multiple accessinterlaces.
 5. The method of claim 1, wherein the signal comprises anuplink signal.
 6. The method of claim 1, wherein a cluster size of thefirst interlace is the same as a cluster size of the second interlace.7. The method of claim 1, wherein a power spectral density of the signalis controlled to avoid exceeding a predetermined limit in anymeasurement interval.
 8. The method of claim 1, wherein control of thepower spectral density is configured to take into account maximum powerspectral density per measurement interval.
 9. The method of claim 1,wherein control of the power spectral density is configured to take intoaccount channel bandwidth.
 10. The method of claim 1, wherein control ofthe power spectral density is configured to take into account requiredpower reduction.
 11. The method of claim 1, wherein the signal iscontrolled cluster-specifically.
 12. The method of claim 1, wherein thesignal is controlled based on cluster-specific power control.
 13. Themethod of claim 1, wherein the signal is controlled based on cluster-specific dropping.
 14. The method of claim 11, wherein thecluster-specific control takes into account an initial unlimitedtransmission power level.
 15. The method of claim 11, wherein thecluster-specific control takes into account a maximum transmission powerlevel within a power spectral density limit.
 16. The method of claim 1,further comprising: determining whether a measurement interval containsmore than one cluster; and applying special handling for predefinedclusters corresponding to the determined measurement interval.
 17. Themethod of claim 16, wherein the special handling is configured to ensurethat a power spectral density limit is fulfilled for the determinedmeasurement interval.
 18. The method of claim 16, wherein the specialhandling comprises at least one of physical resource block dropping,physical resource block specific power reduction, or subcarrierdropping.
 19. An apparatus, comprising: at least one processor; and atleast one memory and computer program code, wherein the at least onememory and the computer program code are configured to, with the atleast one processor, cause the apparatus at least to: configure a firstinterlace having a first starting physical resource block; configure asecond interlace having a second starting physical resource block offsetfrom the first physical resource block; transmit or receive a signalbased on a combination of the first interlace and the second interlace,wherein the combination comprises at least one cluster but less than twoclusters in each measurement interval. 20.-40 (canceled)
 41. A computerprogram product comprising a non-transitory computer-readable storagemedium bearing computer program code embodied therein for use with acomputer, the computer program code comprising code for causing thecomputer to perform operations comprising: configuring a first interlacehaving a first starting physical resource block; configuring a secondinterlace having a second starting physical resource block offset fromthe first physical resource block; and transmitting or receiving asignal based on a combination of the first interlace and the secondinterlace, wherein the combination comprises at least one cluster butless than two clusters in each measurement interval.